Patching road beds

ABSTRACT

A method of patching asphalt and concrete road beds is disclosed comprising the steps of removing debris from a hole in the road bed, filling the hole with a patching material comprised of at least 40% iron metallurgical material having a size of at least 50% between −6 and +100 mesh, and a dilute acidic activator comprised of phosphate anions between 30% and 75%, and combining the iron metallurgical material and the dilute acidic activator to form iron ceramic material.

BACKGROUND AND SUMMARY

Holes in asphalt and concrete road beds, or as commonly known“potholes”, have become a national problem faced by a considerablenumber of drivers every day, especially in dense urban areas with largeseasonal weather changes. For example, the City of New York patched418,000 potholes city wide in 2011 and another 164,000 in the firstthree months of 2012. Poor road conditions are a large and growingfinancial liability for states. Between 2004 and 2008, states spent$16.3 billion annually on repair of roads and highways. In addition,roads in poor condition can negatively impact interstate trade andtravel, the effect of which can be felt across large regions and acrossstate lines. Therefore, road defects, such as holes in asphalt andconcrete road beds, should be repaired quickly and effectively aspossible.

Holes in asphalt and concrete road beds are usually caused by raveling,base failure, poorly compacted material, poor drainage, cracking, and/oraging of the pavement. Potholes are common after rain when waterpenetrates the surface layers of the pavement, softening the underlyingpavement layers, which increases deflections. These holes are alsocommon during thaws when pavements are weaker. Moisture seeps into thepavement, freezes, expands and then thaws, weakening the pavement. Finematerial from the underlying pavement layers is lost, which reduces theoverall structural strength and support for the pavement surface; thus,cracking the pavement surface. Traffic loosens the pavement even more,eventually creating a hole in the road bed.

As asphalt and concrete road beds age and deteriorate, the need forcorrective measures to restore safety and rideability increases. Fundingfor rehabilitation and overlay of these pavements is not likely to keepup with the demand, requiring more government agencies to use the mostcost-effective methods when patching distressed areas. These patchesalso need to survive longer and carry more traffic.

Patching of holes in asphalt and concrete road beds has beentraditionally done by hot patching. Before hot patching a pothole, thehole in the asphalt or concrete road bed needs to be prepared. Thepothole is prepared by removing loose material, drying the area to bepatched, heating tar-based patching material, delivering the heated hottar-based patching material to the hole in the road bed, and compactingthe delivered patching material into the prepared hole in the road bed.As such, hot patching is a time consuming and expensive process. Inaddition, hot patching is heavily regulated because of the workplacerisks.

It has been previously proposed to cold-patch holes in asphalt andconcrete road beds by the system and method described in U.S. Pat. No.7,939,154 (“the '154 Patent). The system and method described in the'154 Patent eliminates the need to heat the tar-based patching material,reduces workplace risks, and reduces the costs of heating the patchingmaterial. However, this patching system and method requires the presenceof at least 55% magnetite (Fe₃O₄) as a reactive iron concentration,which does not include other forms of iron such as hematite (Fe₂O₃),wüstite (FeO) and elemental iron (Fe). In addition, the patchingmaterial disclosed in the '154 Patent has limited application togeographic areas of the country where magnetite is available and torelated areas where the preparing patching material can be shipped atreasonable cost.

Some previously known or proposed methods for patching potholes inasphalt and concrete road beds may have the disadvantage of requiringremoval of water or moisture from the pothole before patching. Thesemethods require cleaning and drying the pothole, applying liquid asphaltto the edges of the pothole, placing the patching material, compactingthe patching material, and cleaning up, resulting in an extremely longand expensive process. When conditions are cold or wet, the materialused to patch holes does not stick well to the surrounding pavementcausing the pavement to crack again, causing the pothole to recur.Therefore, if the pothole was not properly dried before patching, thepothole might reappear only after few days of patching.

Other patching methods may require removing the excess asphalt, applyingan adhesive, adding the asphalt in layers, leveling it off, andcompacting with a pavement roller, which also results in a long andcostly process. See Virginia Department of Transportation. Furthermore,previously known or proposed methods may require the use of differenttypes of patching materials depending on the weather or time of theyear. For example, hot mix asphalt is used in the summer; whereas, acold mix asphalt is used in the winter when hot asphalt plants are notworking. See Utah Department of Transportation Maintenance Division.

As such, there is still a need for a method that provides a durable andcost-effective patching material that is not geographically limited andthat is available in all parts of the country. Moreover, the method forpatching potholes in asphalt and concrete road beds should also providea patching material that is not sensitive to the presence of water,moisture, and oily materials in forming and maintaining the road bedpatch. Furthermore, the method should also provide a patching materialthat can be easily put in place by road maintenance personnel withreduced workplace risks.

Additionally, potholes occur on asphalt and concrete road beds subjectedto a broad spectrum of traffic levels, from two-lane rural routes tomulti-lane interstate highways. Pothole patching may be generallyperformed either as an emergency repair under harsh conditions, or asroutine maintenance scheduled for warmer and drier periods of the year.Patching of holes in asphalt and concrete road beds is done duringweather conditions ranging from clear warm days to harsh cold storms,with temperatures generally ranging anywhere from 38° C. to −18° C. As aresult, there remains a need for an economical method for patchingasphalt and concrete road beds that may be used in any type of weatherconditions.

Currently disclosed is a practical and economical way of patchingasphalt and concrete road beds using iron metallurgical material. Amethod of patching asphalt and concrete road beds is disclosed,comprising the steps of:

(a) removing debris from a hole in the road bed;

-   -   (b) filling the hole with a patching material comprised of at        least 40% iron metallurgical material having a size of at least        50% between −6 and +100 mesh, and a dilute acidic activator        comprised of phosphate anions between 30% and 75%; and    -   (c) combining the iron metallurgical material and the dilute        acidic activator to form iron ceramic material.

The disclosed method of patching asphalt and concrete road beds involvesa patching material comprising in part of iron metallurgical material.In the making of steel, iron metallurgical material dust and sludge iscreated and collected from various sources. A common iron metallurgicalmaterial is mill scale, which is ubiquitous in steelmaking. Mill scaleincludes various forms of iron oxides consisting of iron (II, III),typically comprising between 10% and 58% FeO, and between 38% and 85%Fe₂O₃. Mill scale is formed at the surface of steel by oxidation of thesurrounding atmosphere. See The Making, Shaping and Treating of Steel,at 946-947 (9th Ed. 1971).

Mill scale is formed during heating, hot working and cooling of steelslabs, steel strip, blooms, and billets, as well as most other types ofintermediate and finished steel products. The presence of such millscale is particularly objectionable on the intermediate product to befurther processed. For example, such scale typically must be removed anda clean steel surface provided if satisfactory results are to beobtained from the hot rolling of sheet or strip involving reduction ordeformation of the steel. Similarly, if the steel sheet is for hot orcold drawing applications, the mill scale is removed as its presence onthe steel surface tends to shorten die life, cause irregular anddefective drawing conditions, and cause surface defects on the finishproduct. Mill scale is also removed if the sheet or strip is to beprocessed with a hot dip coating to permit proper alloying and adherenceof the metallic coating, and satisfactory adherence when non-metalliccoatings or paints are to be applied.

Additionally, other sources of iron-containing materials are available.In certain regions, iron-containing mine waste, such as wash-oretailings and red ore tailings may be available for recovery of iron.

Even where not a hazardous waste, mill scale such as Basic OxygenFurnace (BOF) dust and sludge and other iron metallurgical materialshave been typically disposed of in landfills at considerable cost. Theneed for a commercially practical way of using iron metallurgicalmaterial has been emphasized by the public awareness of environmentalissues in solid waste, by the decreasing availability of landfill areas,and by the continuing awareness of the depletion earth's mineralresources. Further, federal and state regulations regarding the use ofthe earth's natural resources and the disposal of waste materials havebecome more encompassing and more restrictive. As a result, thereremains a need for a method for turning readily available ironmetallurgical material into something useful, such as a patchingmaterial for asphalt and concrete road beds.

Mill scale and other iron metallurgical materials are readily availableto provide road patching material since steel making facilities are notlimited to a specific area, but are located throughout the country. Thedisclosed method of patching asphalt and concrete road beds mayadditionally include adding recycled material selected from the groupconsisting of asphalt, concrete and a mixture of asphalt and concrete.The recycled material may be oily. This provides for broad usage oflocally available recycled asphalt, concrete and mixtures thereof fromold road beds. The iron metallurgical material also may be available orprocessed to a material particle size of at least 20% between −14 and+28 mesh.

The patching material may comprise of at least 40% iron metallurgicalmaterial and a dilute acidic activator comprised of phosphate anions. Inone embodiment, the patching material may comprise between 50-80% ironmetallurgical material. In another embodiment, the patching material maycomprise 95% iron metallurgical material. The dilute acidic activatormay comprised phosphate anions between 30% and 75%. In one embodiment,the phosphate anions are formed from dilute phosphoric acid.

The iron metallurgical material is combined with the dilute acidicactivator to form iron ceramic material, which may provide a compressivestrength of at least 900 psi with a 2 inch by 4 inch test cylinder. Inanother embodiment, the iron metallurgical material combined with thedilute acidic activator forming iron ceramic material may provide acompressive strength of at least 1000 psi with a 2 inch by 4 inch testcylinder.

The method of patching asphalt and concrete road beds may include apatching material comprising in addition an antifreeze material. Anantifreeze material is a chemical additive which lowers the freezingpoint of a water-based liquid. An antifreeze material is used to achievefreezing-point depression for cold environments and also achievesboiling-point elevation (“anti-boil”) to allow higher coolanttemperature. In one embodiment, the antifreeze material may be ethyleneglycol. The patching material may include 1-10% wt of antifreezematerial. In another embodiment, the patching material may include 1-2%wt of antifreeze material.

Also disclosed is a method for patching asphalt and concrete road bedsusing iron (II) oxide (FeO) comprising the steps of: (a) removing debrisfrom a hole to be patched in the road bed; (b) filling the hole with apatching material comprised of at least 40% FeO having a size of atleast 50% between −6 and +100 mesh, and a dilute acidic activatorcomprised of phosphate anions between 30% and 75%; and (c) combining theFeO with the dilute acidic activator to form iron ceramic material. Thedilute acidic activator may be phosphoric acid.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrate how holes in asphalt and concrete road beds areformed. It shows a block diagram of one or more embodiments of a methodfor patching asphalt and concrete road beds.

FIG. 2 shows a block diagram of one or more embodiments of a method forpatching asphalt and concrete road beds.

FIG. 3 shows a block diagram of a method for patching asphalt andconcrete road beds using FeO.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to FIGS. 1 through 3, disclosed is a method for patchingasphalt and concrete roads with iron metallurgical material. Fixingholes in asphalt and concrete road beds requires getting deep under theasphalt or concrete surface and providing a material that supports theasphalt or concrete while preventing water from building up under thepavement. FIG. 1 shows how holes in asphalt or concrete road beds areformed. Water from rain, melting snow or ice seeps through cracks in theroad surface, collecting underneath and softening the road base. Waterin the pavement refreezes and expands, forcing up the pavement, on andbelow the surface. The sun dries up the water creating a hole under theroad surface. The soft, fractured asphalt or concrete cannot support theweight of passing vehicles adding extra stress and causing the pavementto break up. As vehicles continue to pass over the weakened spot, theroad surface collapses creating the hole.

FIG. 2 shows a block diagram one or more generalized illustrativeembodiments of a method of patching asphalt and concrete road beds 10using iron metallurgical material. It will be recognized that thepatching asphalt and concrete road beds method 10 is an illustrativeembodiment, and that the present invention is more specificallydescribed in the accompanying claims.

As shown in block 12 of FIG. 2, debris is removed from the road bed.Debris may be any scattered fragments located inside the road bed hole,such as: rock fragments, stripping concrete, loosen asphalt fragments,dust, rubble, wreckage, litter, or discarded garbage or trash. Debrismay be removed by jack hammering. Jack hammering is generally effectivein removing debris and some loosened concrete fragments. Debris may alsobe removed by hot air-blasting. These technique are quite effective atremoving dirt, debris, and laitance. Another technique that may be usedto remove debris from the road bed hole is sandblasting. Sandblasting isquite effective at removing debris, laitance, and loosened concretefragments from the hole in the road bed. This procedure leaves a clean,textured surface that is ideal for bonding.

With reference to block 14 of FIG. 2, the road bed hole is filled with apatching material. The patching material may be delivered to theprepared hole in the road bed and may be sprayed, pumped, or gunned intothe road bed hole. The patching material may comprise of at least 40%iron metallurgical material. The iron metallurgical material may befinely-ground or otherwise physically reduced in particle size. Particlesizes are generally expressed in terms of a mesh size corresponding tothe openings in a sieve. Larger sieve openings (1 in. to ¼ in.) havebeen designated by a sieve “mesh” size that corresponds to the size ofthe opening in inches. Smaller sieve “mesh” sizes of 3½ to 400 aredesignated by the number of openings per linear inch in the sieve. Thefollowing convention is used to characterize particle size by meshdesignation: a “+” before the sieve mesh indicates the desired particlesare retained by the sieve; a “−” before the sieve mesh indicates thedesired particles pass through the sieve; typically 90 percent or moreof the particles will lie within the indicated range. In one embodiment,the iron metallurgical material may have a size of at least 50% between−6 and +100 mesh. In another embodiment, the iron metallurgical materialmay have a size of at least 20% between −14 and +28 mesh.

In one alternative, the iron metallurgical material may be mill scale.Mill scale is a by-product of iron and steel formed during the hotrolling of sheets. Benchiheub et al., Elaboration of iron powder frommill scale, J. Mater. Environ. Sci. 1 (4), 2010, pgs. 267-276. Millscale is a flaky surface of hot rolled steel, iron oxides consisting ofiron (II, III). Dry mill scale particles are generally in the size rangeof between 0.5 mm to 2 mm in diameter. As such, when the ironmetallurgical material comprises of mill scale, the iron metallurgicalmaterial does not need to be finely-ground or otherwise physicallyreduced in particle size. Also, the mill scale may be used even if itcontains some oil.

In another alternative, the iron metallurgical material may comprise amixture of mill scale with other similar iron metallurgical material, asdescribed below, and the mixture may contain more than 55% by weight FeOand FeO equivalent. FeO equivalent is formed from metallic Fe)(Fe°). FeOequivalent is defined as the lesser of:

metallic Fe×3×72/56, or

(total Fe−metallic Fe−(FeO×56/72))×3/2×72/56.

For example, the similar metallurgical material for mixing with millscale may include recyclable iron-bearing material, pellet plant wastesand pellet screened fines. Such pellet plant wastes and pellet screenedfines may include a substantial quantity of hematite. In onealternative, the iron-bearing metallurgical material may include amixture of mill scale and at least one selected from the groupconsisting of processed electric arc furnace (EAF) dust, basic oxygenfurnace (BOF) sludge, blast furnace dust, and mixtures thereof.Alternatively, or in addition, iron bearing material metallurgicalmaterial for mixing with mill scale may include iron ore concentrate,taconite pellets, hematite, magnetite concentrates, oxidized iron ores,and red ore tailings.

With reference to blocks 16 and 18 of FIG. 2, the iron metallurgicalmaterial is combined with a dilute acidic activator comprising ofphosphate anions between 30% and 75% to form iron ceramic material. Inone embodiment, the phosphate anions may be formed from dilutephosphoric acid. Reagent grade phosphoric acid (about 85 weight percentsolution) (i.e., without dilution) may be used. The phosphoric acid maybe diluted with at least some water. In another embodiment, thephosphate anions may be formed from an acid phosphate, such as ammoniumphosphate solution.

The iron metallurgical material and the dilute acidic activator arecombined to form iron ceramic material. The iron ceramic material isformed by the reaction of the metal cation with the phosphate anions.The reaction is attained by mixing a cation donor, generally an oxidesuch as iron oxide, with a acidic activator, such as phosphoric acid oran acid phosphate such as ammonium phosphate solution.

The reaction between the dilute acidic activator and the ironmetallurgical material results in a rapid-setting iron ceramic material.The setting time may be increase by further diluting the acidicactivator. The iron ceramic material cures rapidly because of anexothermic reaction with the phosphate. The result is a durable andresistant iron ceramic material that may be use as a patching materialin a method for patching asphalt and concrete road beds even attemperatures below freezing.

Compressive strengths for the iron ceramic material were determinedfollowing U.S. DOT Standard Compression Tests for both concretecylinders and asphalt cylinders. The compressive strengths ofcylindrical concrete specimens were determined using the ASTM C39 andAASHTO-T22 test methods. These methods consist of applying a compressiveaxial load to molded cylinders or cores at a rate which is within aprescribed range until failure occurs. The compressive strength of thespecimen is calculated by dividing the maximum load attained during thetest by the cross-sectional area of the specimen. The compressivestrengths of compacted asphalt mixtures were determined using theAASHTO-T167 test method. The iron metallurgical material combined withthe dilute acidic activator forming iron ceramic material may provide acompressive strength of at least 900 psi with a 2 inch by 4 inch testcylinder. In another embodiment, the iron metallurgical materialcombined with the dilute acidic activator forming iron ceramic materialmay provide a compressive strength of at least 1000 psi with a 2 inch by4 inch test cylinder.

The following examples are offered to further illustrate variousspecific embodiments and techniques of the present invention. It shouldbe understood, however, that many variations and modificationsunderstood by those of ordinary skill in the art may be made whileremaining within the scope of the present invention. Therefore, thescope of the invention is not intended to be limited by the followingexamples.

In one example, 85 wt % of mill scale was mixed with 5 wt % of dilutephosphoric acid to mill scale for about 1-3 minutes and was set within5-6 minutes. The cure time was approximately 30 minutes. The reactionresulted in a solid iron ceramic material with a compressive strength ofat least 1000 psi. Complete hardening of the solid iron ceramic materialwas obtained between 8-12 hours. While the iron ceramic material washardening, an exothermic reaction was observed. The exothermic reactioncaused the patching material to heat up slightly to between 100-120° F.During this process, no smells were emitted from the reaction componentsor reaction products.

In another example, 90 wt % of mill scale was mixed with 10 wt % ofdilute phosphoric acid for about 1-3 minutes and was set within 5-6minutes. The cure time was approximately 30 minutes. The reactionresulted in a solid iron ceramic material with a compressive strength ofat least 1000 psi. Same as above, complete hardening of the solid ironceramic material was obtained between 8-12 hours. While the iron ceramicmaterial was hardening, an exothermic reaction was observed. Theexothermic reaction caused the patching material to heat up slightly tobetween 100-120° F. During this process, no smells were emitted from thereaction components or reaction products.

In another example, 95 wt % of mill scale was mixed with 15 wt % ofdilute phosphoric acid for about 1-3 minutes and was set within 5-6minutes. The cure time was approximately 30 minutes. The reactionresulted in a solid iron ceramic material with a compressive strength ofat least 1000 psi. Similar to the examples above, complete hardening ofthe solid iron ceramic material was obtained between 8-12 hours. Whilethe iron ceramic material was hardening, an exothermic reaction wasobserved. The exothermic reaction caused the patching material to heatup slightly to between 100-120° F. During this process, no smells wereemitted from the reaction components or reaction products.

As mentioned above, presently used methods for patching asphalt andconcrete roads require for the hole to be dried up first to remove anymoisture before adding any patching material. If moisture is present,then the patching material does not bond well to the surrounding asphaltor concrete, which causes for the hole to reappear after a short periodof time. The currently disclosed method does not require for moisture tobe removed from the hole before adding the patching material. Thecurrently disclosed patching material binds well to the surrounding roadmaterial because moisture is one of the components of the patchingmaterial (i.e. dilute acidic activator, e.g. dilute phosphoric acid).Therefore, contrary to presently known methods, even if the pothole isnot dried and contains moisture, the patching material will absorb anysurrounding moisture and will effectively bind to the surroundingasphalt or concrete.

The reaction between the patching material with the dilute acidicactivator causes the patching material to expand slightly. Thisexpansion occurs as the patch is setting and helps the patching materialto get into the edges of the hole forming a durable contact between thepatch and the asphalt or concrete edges of the hole as the patchingmaterial hardens. As such, contrary to previously known methods, thecurrently disclosed method does not require for holes to have fourstraight edges before adding the patching material.

When holes develop in the asphalt or concrete road beds, prompt actionis required to correct the defect before the pothole increases in sizeand severity. The currently disclosed method provides an effective andfast way of fixing holes in asphalt and concrete road beds. Once thepatching material comprising of iron metallurgical material and diluteacidic activator reacts in the pothole in the road bed to form ironceramic material, the patching material starts to hardened within 5 to 6minutes. The cure time is about 30 minutes. And complete hardening isachieved between approximately 8 to 12 hours.

With reference to block 20 of FIG. 2, the patching material may beoptionally compacted into the road bed. The patching material may beslightly compacted or tamped down with a tamping tool to get a levelpatch which is even with the surface of the road. Compaction provides atighter patch for traffic than simply leaving the loose material. Thereacted patching material may be compacted using truck tires.Alternatively, the patching material may be compacted with a devicesmaller than the patch area, such as single-drum vibratory rollers andvibratory plate compactors.

One of the major problems that authorities face when fixing holes inasphalt and concrete road beds is that the currently available patchingmethods work best in warm weather, like spring and summer. The idealtime to patch holes in road beds is summer when things are fluid andsticky. In winter, presently known patching materials congeal and arenot easy to work with. For example, hot patching does not bond well withdramatically colder pavement in cold winter weather, including abovefreezing temperatures. See City of Columbus, Ohio—Department of PublicService. The hot patch shrinks away from, and does not conform to, thesurrounding asphalt and the contours inside the pothole. The problemwith this is that potholes also occur in cold weather, like winter.Therefore, authorities use cold patch to fix potholes in the winter. Theproblem with cold patching is that it is a temporary fix designed torepair potholes until they can be hot patched during warmer weather inthe spring and summer if the cold patched hole reopens. Consequently,even though they will have to fix the holes again in a short period oftime after, authorities do not have a choice if they want to keep lanessafe for drivers. This practice results in millions of dollars beingwasted. The currently disclosed method of patching asphalt and concreteroad beds may be used in both cold weather and hot weather.

The method of patching asphalt and concrete road beds may include apatching material comprising in addition an antifreeze material. Theantifreeze material may be ethylene glycol. The addition of anantifreeze material provides further assurance that the currentlydisclosed method may be performed regardless of the weather or climaticconditions and below the freezing point of water.

The method of patching asphalt and concrete road beds may additionallyinclude adding recycled material selected from the group consisting ofasphalt, concrete and a mixture of asphalt and concrete. The recycledmaterial may be oily. As such, the recycled material does not need to beheated to remove the oil, which decreases the operational costs. Thisprovides for broad usage of locally available recycled asphalt, concreteand mixtures thereof from old road beds. The recycled material iscrushed and screened. In one embodiment, the recycled material may behave a size of at least −6 mesh. In another embodiment, the recycledmaterial may be have a size of at least −10 mesh.

In one embodiment, the iron metallurgical material combined with diluteacidic activator forming iron ceramic material may provide a compressivestrength of at least 1000 psi with a 2 inch by 4 inch test cylinder. Inanother embodiment, the iron metallurgical material combined with diluteacidic activator forming iron ceramic material may provide a compressivestrength of at least 1200 psi with a 2 inch by 4 inch test cylinder.

The recycled material may be added to the iron metallurgical material toform a dry mixture. In one embodiment, the dry mixture may comprise ofbetween 40-60% mill scale and 40-60% recycled material. The dry mixtureis then combined with the dilute acidic activator comprised of phosphateanions forming iron ceramic material.

In one example, 10 wt % of dilute acidic activator was added to drymixture of iron metallurgical material and recycled material. Theresulting mixture was mixed for about 1-3 minutes and was set within 5-6minutes. The cure time was approximately 30 minutes. The reactionresulted in a solid iron ceramic material with a compressive strength ofat least 1000 psi. Complete hardening of the solid iron ceramic materialwas obtained between 8-12 hours. While the iron ceramic material washardening, an exothermic reaction was observed. The exothermic reactioncaused the patching material to heat up slightly to between 120-140° F.During this process, no smells were emitted from the reaction componentsor reaction products.

The recycled material provides a better bond to the surrounding edges ofthe hole in the road bed. Furthermore, the addition of recycled materialto the iron metallurgical material and dilute acidic activator makes theformed iron ceramic material more flexible, which increases the patchingmaterial durability.

The recycled material may comprise of organic road binder, which areoften oily. The mill scale may also comprise of oily material. Thepresence of these oily materials does not have a detrimental effect onthe road patching material. The currently disclosed patching materialbinds well to all types of road material and sticks to the edges of theroad bed hole. The method provides a patching material that is alsounreceptive to water; thus, it may be used under any type of weather.

Referring now to FIG. 3, also disclosed is a method 32 for patchingasphalt and concrete road beds using iron(II) oxide (FeO) comprising thesteps of: (a) removing debris from a hole in the road bed; (b) fillingthe hole with a patching material comprised of at least 40% FeO having asize of at least 50% between −6 and +100 mesh, and a dilute acidicactivator comprised of phosphate anions between 30% and 75%; and (c)combining the FeO with the dilute acidic activator to form iron ceramicmaterial.

As shown in block 22 of FIG. 3, debris is removed from the road bed.Debris may be any scattered fragments located inside the road bed hole,such as: rock fragments, stripping concrete, loosen asphalt fragments,dust, rubble, wreckage, litter or discarded garbage or trash.

With reference to block 24 of FIG. 3, the pothole is filled with apatching material. The patching material may be delivered to the hole inthe road bed and may be sprayed, pumped, or gunned into the road bedhole. The patching material may comprise of at least 40% FeO. FeO may befinely-ground or otherwise physically reduced in particle size.

With reference to blocks 26 and 28 of FIG. 3, FeO is mixed with a diluteacidic activator comprising of phosphate anions between 30% and 75% toform iron ceramic material. The dilute acidic activator may be dilutephosphoric acid. The iron ceramic material is formed by the reaction ofthe metal cation with the phosphate anions. The reaction is attained bymixing a cation donor, generally an oxide such as iron oxide, with aacidic activator, such as phosphoric acid or an acid phosphate, such asammonium phosphate solution. The reaction between the dilute acidicactivator and FeO results in a rapid-setting iron ceramic material. Theiron ceramic material cures rapidly because of the exothermic reactionwith the phosphate. The result is a durable and resistant iron ceramicmaterial that may be use as a patching material in a method for patchingasphalt and concrete road beds even at temperatures below freezing.

FeO combined with dilute acidic activator forming iron ceramic materialmay provide a compressive strength of at least 1000 psi with a 2 inch by4 inch test cylinder. In another embodiment, FeO combined with diluteacidic activator forming iron ceramic material may provide a compressivestrength of at least 1200 psi with a 2 inch by 4 inch test cylinder.

The method for patching asphalt and concrete road beds may furthercomprise adding recycled material selected from the group consisting ofasphalt, concrete and a mixture of asphalt and concrete. The recycledmaterial is crushed and screened. In one embodiment, the recycledmaterial may be have a size of at least −6 mesh. In another embodiment,the recycled material may be have a size of at least −10 mesh.

The recycled material may be added to FeO to form a dry mixture. In oneembodiment, the dry mixture may comprise of between 40-60% mill scaleand 40-60% recycled material. The dry mixture is then mixed with thedilute acidic activator comprised of phosphate anions forming ironceramic material. In one example, 10 wt % of dilute acidic activator wasadded to dry mixture. The resulting mixture was mixed for about 1-3minutes and was set within 5-6 minutes. The cure time was approximately30 minutes. The reaction resulted in a solid iron ceramic material witha compressive strength of at least 1000 psi. Complete hardening of thesolid iron ceramic material was obtained between 8-12 hours. While theiron ceramic material was hardening, an exothermic reaction wasobserved. The exothermic reaction caused the patching material to heatup slightly to between 120-140° F. During this process, no smells wereemitted from the reaction components or reaction products.

With reference to block 30 of FIG. 3, the patching material may beoptionally compacted into the road bed. The reacted patching materialmay be slightly compacted or tamped down with a tamping tool to get alevel patch which is even with the surface of the road. Compactionprovides a tighter patch for traffic than simply leaving the loosematerial. The reacted patching material may be compacted using trucktires. Alternatively, the patching material may be compacted with adevice smaller than the patch area, such as single-drum vibratoryrollers and vibratory plate compactors.

The method of patching asphalt and concrete road beds may furtherinclude the addition of an antifreeze material. The addition of anantifreeze material provides further assurance that the currentlydisclosed method may be performed regardless of the weather or climaticconditions and below the freezing point of water.

The currently disclosed method provides a patching material that bindswell to all types of road material and sticks to the edges of the roadbed hole. The patching material is also unreceptive to water; thus, itmay be used under any type of weather.

Although the invention has been described in detail with reference tocertain embodiments, it should be understood that the invention is notlimited to the disclosed embodiments. Rather, the present inventioncovers variations, modifications and equivalent structures that existwithin the scope and spirit of the invention and such are desired to beprotected.

What is claimed is:
 1. A method of patching asphalt and concrete roadbeds comprising the following steps: (a) removing debris from a hole ina road bed; (b) filling the hole with a patching material comprised ofat least 40% iron metallurgical material having a size of at least 50%between −6 and +100 mesh, and a dilute acidic activator comprised ofphosphate anions between 30% and 75%; and (c) combining the ironmetallurgical material and the dilute acidic activator to form ironceramic material.
 2. The method of patching asphalt and concrete roadbeds of claim 1 further comprising adding recycled material selectedfrom the group consisting of asphalt, concrete and a mixture of asphaltand concrete.
 3. The method of patching asphalt or concrete road beds ofclaim 2 where the recycled material is oily.
 4. The method of patchingasphalt and concrete road beds of claim 1 where the combined ironmetallurgical material and dilute acidic activator forming iron ceramicmaterial provide a compressive strength of at least 1000 psi with a 2inch by 4 inch test cylinder.
 5. The method of patching asphalt andconcrete road beds of claim 2 where the combined iron metallurgicalmaterial and dilute acidic activator forming iron ceramic materialprovide a compressive strength of at least 1000 psi with a 2 inch by 4inch test cylinder.
 6. The method of patching asphalt and concrete roadbeds of claim 1 where the iron metallurgical material has a size of atleast 20% between −14 and +28 mesh.
 7. The method of patching asphaltand concrete road beds of claim 1 where the patching material comprisesin addition an antifreeze material.
 8. The method of patching asphaltand concrete road beds of claim 1 where the phosphate anions are formedfrom dilute phosphoric acid.
 9. A method of patching asphalt andconcrete road beds comprising the following steps: (a) removing debrisfrom a hole in the road bed; (b) filling the hole with a patchingmaterial comprised of at least 40% FeO having a size of at least 50%between −6 and +100 mesh, and a dilute acidic activator comprised ofphosphate anions between 30% and 75%; and (c) combining the FeO and thedilute acidic activator to form iron ceramic material.
 10. The method ofpatching asphalt and concrete road beds of claim 9 further comprisingadding recycled material selected from the group consisting of asphalt,concrete and a mixture of asphalt and concrete.
 11. The method ofpatching asphalt or concrete road beds of claim 10 where the recycledmaterial is oily.
 12. The method of patching asphalt and concrete roadbeds of claim 9 where the combined iron metallurgical material anddilute acidic activator forming iron ceramic material provide acompressive strength of at least 1000 psi with a 2 inch by 4 inch testcylinder.
 13. The method of patching asphalt and concrete road beds ofclaim 10 where the combined iron metallurgical material and diluteacidic activator forming iron ceramic material provide a compressivestrength of at least 1000 psi with a 2 inch by 4 inch test cylinder. 14.The method of patching asphalt and concrete road beds of claim 9 wherethe FeO has a size of at least 20% between −14 and +28 mesh.
 15. Themethod of patching asphalt and concrete road beds of claim 9 where thepatching material comprises in addition an antifreeze material.
 16. Themethod of patching asphalt and concrete road beds of claim 9 where thephosphate anions are formed from dilute phosphoric acid.
 17. A patchingmaterial for asphalt and concrete road beds comprising: a patchingmaterial comprised of at least 40% iron metallurgical material having asize of at least 50% between −6 and +100 mesh; and an dilute acidicactivator comprised of phosphate anions between 30% and 75%.
 18. Thepatching material for asphalt and concrete road beds as claimed in claim17 where the iron metallurgical material is combined with the diluteacidic activator to form iron ceramic material.
 19. The patchingmaterial for asphalt and concrete road beds as claimed in claim 17further comprising a recycled material selected from the groupconsisting of asphalt, concrete and a mixture of asphalt and concrete.20. The patching material for asphalt and concrete road beds as claimedin claim 19 where the iron metallurgical material, the dilute acidicactivator, and the recycled material are combined to form iron ceramicmaterial.
 21. The patching material for asphalt and concrete road bedsas claimed in claim 19 where the recycled material is oily.
 22. Thepatching material for asphalt and concrete road beds as claimed in claim18 where the combined iron metallurgical material and dilute acidicactivator forming iron ceramic material provide a compressive strengthof at least 1000 psi with a 2 inch by 4 inch test cylinder.
 23. Thepatching material for asphalt and concrete road beds as claimed in claim20 where the combined iron metallurgical material, the dilute acidicactivator, and the recycled material forming iron ceramic materialprovide a compressive strength of at least 1000 psi with a 2 inch by 4inch test cylinder.
 24. The patching material for asphalt and concreteroad beds as claimed in claim 17 where the iron metallurgical materialhas a size of at least 20% between −14 and +28 mesh.
 25. The patchingmaterial for asphalt and concrete road beds as claimed in claim 17 wherethe patching material comprises in addition an antifreeze material. 26.The patching material for asphalt and concrete road beds as claimed inclaim 17 where the phosphate anions are formed from dilute phosphoricacid.
 27. A patching material for asphalt and concrete road bedscomprising: a patching material comprised of at least 40% FeO having asize of at least 50% between −6 and +100 mesh; and an dilute acidicactivator comprises phosphate anions between 30% and 75%.
 28. Thepatching material for asphalt and concrete road beds as claimed in claim27 where the iron metallurgical material is combined with the diluteacidic activator to form iron ceramic material.
 29. The patchingmaterial for asphalt and concrete road beds as claimed in claim 27further comprising a recycled material selected from the groupconsisting of asphalt, concrete and a mixture of asphalt and concrete.30. The patching material for asphalt and concrete road beds as claimedin claim 29 where the iron metallurgical material, the dilute acidicactivator, and the recycled material are combined to form iron ceramicmaterial.
 31. The patching material for asphalt and concrete road bedsas claimed in claim 29 where the recycled material is oily.
 32. Thepatching material for asphalt and concrete road beds as claimed in claim28 where the combined iron metallurgical material and dilute acidicactivator forming iron ceramic material provide a compressive strengthof at least 1000 psi with a 2 inch by 4 inch test cylinder.
 33. Thepatching material for asphalt and concrete road beds as claimed in claim30 where the combined iron metallurgical material, the dilute acidicactivator, and the recycled material provide a compressive strength ofat least 1000 psi with a 2 inch by 4 inch test cylinder.
 34. Thepatching material for asphalt and concrete road beds as claimed in claim27 where the iron metallurgical material has a size of at least 20%between −14 and +28 mesh.
 35. The patching material for asphalt andconcrete road beds as claimed in claim 27 where the patching materialcomprises in addition an antifreeze material.
 36. The patching materialfor asphalt and concrete road beds as claimed in claim 27 where thephosphate anions are formed from dilute phosphoric acid.
 37. A methodfor preparing a patching material for filling holes in asphalt andconcrete road beds comprising the steps of: (a) adding phosphate andwater to form an acidic activator; and (b) combining the acidicactivator with a patching material comprised of at least 40% ironmetallurgical material having a size of at least 50% between −6 and +100mesh.
 38. The method for preparing a patching material for filling holesin asphalt and concrete road beds as claimed in claim 37 furthercomprising adding an antifreeze material to the patching material. 39.The method for preparing a patching material for filling holes inasphalt and concrete road beds as claimed in claim 37 where thephosphate anions are formed from dilute phosphoric acid.
 40. The methodfor preparing a patching material for filling holes in asphalt andconcrete road beds as claimed in claim 37 where the iron metallurgicalmaterial has a size of at least 20% between −14 and +28 mesh.
 41. Amethod for preparing a patching material for filling holes in asphaltand concrete road beds comprising the steps of: (c) adding phosphate andwater to form an acidic activator; (d) combining the acidic activatorwith a patching material comprised of at least 40% FeO having a size ofat least 50% between −6 and +100 mesh.
 42. The method for preparing apatching material for filling holes in asphalt and concrete road beds asclaimed in claim further 41 comprising adding an antifreeze material tothe patching material.
 43. The method for preparing a patching materialfor filling holes in asphalt and concrete road beds as claimed in claim41 where the phosphate anions are formed from dilute phosphoric acid.44. The method for preparing a patching material for filling holes inasphalt and concrete road beds as claimed in claim 41 where the ironmetallurgical material has a size of at least 20% between −14 and +28mesh.